• Computational Structural Engineering
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• v.3 no.3
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• pp.141-146
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• 1990

This study is on a seismic analysis of absorber rod in KMRR Reactivity Control Mechanism. The model being studied is two coaxial tubes(control absorber rod and flow tube) immersed in the water and partially coupled(overlap) by water gap. The hydrodynamic mass effects by the water in each surrounding conditions are considered in the model. The natural frequencies, stresses and displacements of the system due to Safe Shutdown Earthquake are computed in the cases of in-phase modes and out-of-phase modes of two coaxial tubes. The results show that maximum stresses are well below the allowable limit but the maximum displacements at the ends of both tubes are so much that the absorber rod contacts with the flow tube(or surrounding wall).

• Korean Journal of Pharmacognosy
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• v.31 no.1
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• pp.82-86
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• 2000

To evaluate anti-influenza virus activity of 113 specimens of Korean traditional medicine both water and methanol extracts were examined using haemagglutination inhibition test. The water extract from Citrus junos was found to inhibit influenza virus A/Taiwan/l/86(H1N1). The survival rates of virus were determined by in situ cellular enzyme-linked immunosorbent assay. The water extract of Citrus junos was fractionated by chromatographic separating using Amberlite XAD-4, 40% MeOH and 60% MeOH layer had antiviral activity. The half inhibition concentration $(IC_{50})$ of 40% MeOH layer on survival of influenza virus was $MIC>361.5{\mu}g/ml$ and $IC_{50}$ value of fr. 40-4 fractionated from 40% MeOH layer was $677.19{\mu}g/ml$. These results suggested that the fractions of Citus junos have potent anti-influenza A virus activity.

• New & Renewable Energy
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• v.1 no.2 s.2
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• pp.53-59
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• 2005

Objective of the research is to demonstrate solar thermal space and ground heating system which is integrated to a green-house culture facility for reducing healing cost, Increasing the value of product by environment control, and developing advanced culture technology by deploying solar thermal system. Field test for the demonstration was carried out in horticulture complex In Jeju Island. Medium scale solar hot water system was installed in a ground heating culture facility. Reliability and economic aspect of the system which was operated complementary with thermal storage and solar hot water generation were analyzed by investigating collector efficiency, operation performance, and control features. Short term day test on element performance and Long term test of the whole system were carried out. Optimum operating condition and its characteristics were closely Investigated by changing the control condition based on the temperature difference which Is the most important operating parameter For establishing more reliable and optimal design data regarding system scale and operation condition, continuous operation and monitoring on the system need to be further carried out. However, It is expected that, in high-insolation areas where large-scale ground storage is adaptable, solar system demonstrated in the research could be economically competitive and promisingly disseminate over various application areas.

• Journal of Energy Engineering
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• v.6 no.2
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• pp.170-175
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• 1997

An experimental study was carried out with the Mock-up made for the improved water level control of the steam generator in nuclear power plant and for the confirmation of swell/shrink status of the water level by opening and closing the steam dump valve. We can confirmed the possibility of using the Mock-up by introducing the PI controller and the FUZZY controller. Accordingly, we can confirmed that the practical usability of advanced controllers, which will be developed for the improved water level control of the steam generator in nuclear power plant by using the Mock-up.

• Journal of the Korean Applied Science and Technology
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• v.35 no.1
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• pp.284-291
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• 2018

In this study, a dust inhibitor for road dust was prepared by using molecular structure, molecular weight, viscosity, hydrophilicity, swelling, wetting and moisturizing properties of natural polysaccharide which is widely used as food and cosmetic materials. Various dust control effects were confirmed and superior results were obtained than simple water spraying and synthetic for control(PVA). In addition, the comparison of water evaporation, scattering inhibition rate, Field test, and determining acute lethality of effluents to Daphnia magna were studied and the safety of soil and water quality was studied. The availability of the dust inhibitor was confirmed.

• Hwankyungkyoyuk
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• v.22 no.2
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• pp.79-91
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• 2009

The purpose of this study is to find out the influence of the urban stream investigation on elementary school students' environmental conservation awareness. The urban stream investigation was applied to the experimental group and the control group has been taught by the traditional teaching method focused on the teacher's lecture. To analyze the effect of urban stream investigation, the pre- and post-tests on environmental conservation awareness composed of interest in living things, perception about water pollution and environmental conservation were applied to the both groups. The results were analyzed by One-way ANOVA and ANCOVA. As a result, there were not significant difference between the experimental and the control group in the pretest(p>.05). In the post-tests on the student's interest in living things, perception about water pollution and environmental conservation the scores of the experimental group were higher than those of the control group(p<0.05). Therefore, the urban stream investigation made a positive effect on improving of elementary school students' environmental conservation awareness.

• Journal of the Korea Concrete Institute
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• v.12 no.5
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• pp.111-120
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• 2000

In case of constructing concrete structure under water, generally concrete mixed with antiwashout admixture, high range water reducer, or AE-water reducing agent etc has been manufactured to ensure the quality of antiwashout underwater concrete because of being difficulty in ascertaining construction situation by the naked eye. The properties of high quality antiwashout underwater concrete that were aimed at affluent fluidity, workability and the compressive strength of 450 kgf/$\textrm{cm}^2$ at 28 ages using two types of blended cements are following as;(1) Setting time of antiwashout underwater concretes using blended cements was more greatly delayed than that of control concrete, however, was satisfied with criteria value of "Quality standard specification of antiwashout admixture for concrete".(2) As a test results of slump flow, efflux time and box elevation of head, it was found that workability of high quality antiwashout underwater concrete was improved. (3) Heat evolution amount of OPC was 1.5 times as high as that of two types of bended cements in 72 hours. (4) Suspended solids of antiwashout underwater concrete using blended cements was more than that of control concrete, also compressive strength of high quality antiwashout underwater concrete was very low in early age, but was better than that of control concrete as to increasing ages.

• Korean Journal of Environmental Agriculture
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• v.33 no.1
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• pp.30-36
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• 2014

BACKGROUND: Best management practices are often implemented to control nonpoint source pollutants. Best management practices need to be simulated and analyzed for effective Best management practices implementations. Filter strip is one of effective Best management practices in agricultural areas. METHODS AND RESULTS: Soil and Water Assessment Tool model was selected to explore the effectiveness of filter strip to control total phosphorous in Golji watershed. Soil and Water Assessment Tool model was calibrated for flow and total phosphorous by Sequential Uncertainty Fittin ver.2 algorithm provided in Soil and Water Assessment Tool-Calibration and Uncertainty Procedures. Three scenarios defined by filter strip width were applied. The filter strip width of 5 m was able to reduce the most amount of total phosphorous. In other words, the total phosphorous reduction by filter strip of 5 m was 28.0%, while the reduction was 17.5% by filter strip of 1 m. However, the reduction per unit filter strip width were 17.4%, 8.0%, and 4.5% for 1 m, 3 m, and 5 m of filter strips, respectively. CONCLUSION: Best management practices need to be simulated and analyzed so that the BMP scenario can be cost-effective. A large size of BMP might be able to control large amount of pollutants, however it would not be indicated as a cost-effective strategy.

• Journal of Korean Society on Water Environment
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• v.31 no.4
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• pp.407-417
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• 2015

Soil loss is one of the significant disasters which have threatened human community and ecosystem. Particularly, Korea has high vulnerability of soil loss because rainfall is concentrated during summer and mountainous regions take more than 70% of total land resources. Accordingly, the sediment control management plan are required to prevent the loss of soil resources and to improve water quality in the receiving waterbodies. In this regard, the objectives of this study are 1) to quantify the effect of the Vegetative Filter Strip (VFS) on sediment runoff reduction and 2) to analyze the relationship of rainfall intensity and sediment runoff. For this, SATEEC and VFSMOD were used to estimate sediment runoff according to rainfall intensity and to quantify the effect of VFS on sediment runoff reduction, respectively. In this study, the VFS has higher impact on sediment reduction for lower maximum rainfall intensity, which means that the maximum rainfall intensity is one of significant factors to control sediment runoff. Also, the sediment with VFS considered was highly correlated with maximum rainfall intensity. For these results, this study will contribute to extend the applicability of VFS in establishing eco-friendly sediment control plans.

• Journal of Korean Society of Water and Wastewater
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• v.33 no.6
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• pp.457-467
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• 2019

Because non-point source pollution is very closely related to hydrological characteristics, its importance is highly emphasized nowadays along with accelerating climate change. Especially for Korea, the non-point source pollution and its control are entirely depending on runoff, precipitation, drainage, land use or development, based on geographical and topographical reasons of Korea. Many studies reported the physical (e.g., apparatus- and natural-type facilities, etc.) and chemical methods (e.g., organic and inorganic coagulants, etc.) of controling non-point pollutant source pollution, however, those are needed to be reconsidered along with climate change causing the unexpected patterns and amounts of precipitation and strengthen complexity of social community. The objectives of this study are to assess recent situations of non-point source pollution in Korea and its control means and to introduce possible effective ways of non-point source pollution against climate change in near future.